Susanna Kaysen (Ryder), 18 years old in April 1967, “voluntarily” (her parents essentially force her to go there, and she is not free to leave until the staff approves her release) checks herself into the fictitious Claymoore Hospital (based on McLean Hospital, the actual institution featured in the memoir), after an overdose of aspirin and her stay extends for over a year.

She befriends fellow patients Polly “Torch” Clark (Elisabeth Moss), a burn victim; Georgina Tuskin (Clea DuVall), a pathological liar; Daisy Randone (Brittany Murphy), a sexually abused girl with an eating disorder and who cuts herself; Janet Webber (Angela Bettis), an anorexic; Cynthia Crowley (Jillian Armenante), whose only disorder seems to be a proclivity to dress like men and is there because her parents don’t want to see her; and others, and forms a small troupe of troubled women in her ward. Susanna is enchanted in particular by Lisa Rowe (Angelina Jolie), who has been diagnosed as a sociopath (as in the book, it is left to interpretation whether she actually is one). Lisa is a force to be reckoned with: she is magnetic, rebellious, won’t take her medication and verbally abuses the other patients. Lisa befriends Susanna and together they start causing trouble. Lisa encourages Susanna to stop taking her medications and/or trade them with others, and generally resist the influences of therapy (referred to by the patients as “ther-rape-me”).

…

At the end of the film, Susanna states that by the 1970s, most of her friends were released and some she saw and some never again. But there wasn’t a day “her heart doesn’t find them.”

When a young American girl, Sophie (Amanda Seyfried) travels to the city of Verona, Italy home of the star-crossed lovers of Juliet Capulet and Romeo Montague fame, she finds an unanswered “letter to Juliet”, one of thousands of letters left at the fictional lover’s Verona courtyard. She inspires its author, Claire (Vanessa Redgrave) to search for her long-lost love which sets off a chain of events that will bring a love into both their lives unlike anything they have ever imagined.

Note: This plot is for the non-censored version of the film. Some scenes described below are omitted from other versions.

In 17th Century France, Cardinal Richelieu (Christopher Logue) is influencing Louis XIII (Graham Armitage) in an attempt to gain further power. He convinces Louis that the fortifications of cities throughout France should be demolished to prevent Protestants from uprising. Louis agrees, but forbids Richelieu from carrying out demolitions in the town of Loudun, having made a promise to its governor not to damage the town.

Meanwhile, in Loudun, the Governor has died, leaving control of the city to Urbain Grandier (Oliver Reed), a dissolute and proud but popular and well-regarded priest. He is having an affair with a relative of Father Canon Mignon (Murray Melvin), another priest in the town, unaware that the deformed, neurotic Sister Jeanne (Vanessa Redgrave), head of the local convent, is sexually obsessed with him. She asks for Grandier to become the convent’s new confessor. Grandier secretly marries another woman, Madeline De Brou (Gemma Jones), but news of this reaches Sister Jeanne, driving her to insanity (this includes an attack where Sister Jeanne viciously attacks Madeleine when the latter brings back a book that the former had lent her, and Sister Jeanne accuses Madeleine of being a “sacrilegious bitch”, among other things).

…

After the execution, Barre leaves to continue his activities elsewhere (the place mentioned by Laubardemont to Sister Jeanne is nearby Poitier). Laubardemont informs Sister Jeanne that Mignon has been put away in a sanatorium for claiming that Grandier was innocent (the explanation given is that he is demented), and that “with no signed confession to prove otherwise, everyone has the same opinion”. He gives her one of Grandier’s charred bones and leaves. Sister Jeanne, now completely broken, masturbates pathetically with the charred femur. Grandier’s wife, having been released is seen walking away from the ruined city as the film ends.

At a star party, Amateur astronomer Leo Biederman (Wood) stumbles upon unusual object near the stars Mizar and Alcor, and alerts professional astronomer Dr. Marcus Wolf (Charles Martin Smith) at a local observatory. After discovering the object is a comet and working out its orbit, Wolf realizes that the comet will impact Earth, but dies in a car accident on his way down from the observatory before he can alert the world.

A year later, MSNBC reporter Jenny Lerner (Leoni) researches the resignation of the United States Secretary of the Treasury and his connection to an “Ellie.” She soon discovers that Ellie is not a mistress but “E.L.E.”, an acronym for “extinction-level event”. Because of Lerner’s investigation, President of the United States Tom Beck (Freeman) announces the grim facts: The cometâ€”named Wolf-Biedermanâ€”is 7 miles (11 km) wide, large enough to destroy civilization if it strikes Earth. He also reveals that The United States and Russia have been secretely constructing the largest spacecraft ever in orbit: The Messiah. They plan to send the Messiah to destroy the comet, using nuclear weapons. Life changes drastically worldwide, and Leo and Lerner both become celebrities.

After intercepting and landing on the comet, The Messiah’s crew (Duvall and others) plants the bombs into the comet’s surface, but one crew member dies and another is seriously injured. When the bombs are detonated Messiah is damaged and contact with Earth is lost. The comet is not destroyed; instead, it splits into two chunks, one a mile and a half wide (named “Biederman”) and the other six miles wide (“Wolf”), but both still world-threatening.

…

The film closes with Beck speaking to a large crowd in front of the under-reconstruction United States Capitol, in which he urges the nation to continue its recovery and efforts to rebuild.

Claire tries to persuade Phelps not to kill Hunt, but he kills her instead, knocks Hunt down, and climbs up to the roof. Krieger has been following the train in a helicopter and is waiting to extract Phelps. Hunt recovers and follows Phelps, impeding his efforts to escape and tethering Krieger’s helicopter to the train as it heads into the Channel Tunnel. The fight continues, with the helicopter now following the train inside the tunnel. The two fight atop the wind-swept train before Phelps disconnects the helicopter from the train and attempts to escape. Hunt follows, leaping onto the helicopter’s landing skids and attaching explosive chewing gum to the windshield. The ensuing explosion kills Phelps and Krieger, with Ethan narrowly escaping. Now in possession of the NOC list and Max’s true identity, Kittridge reinstates Stickell as an IMF agent and drops his investigation against Hunt, who resigns from the IMF. As he flies home, a flight attendant approaches him and asks, through a coded phrase, if he is ready to take on a new mission.

The film comprises four parts, corresponding to the four parts of the novel. Some scenes are shown several times from different perspectives.

Briony Tallis (Saoirse Ronan) is a 13-year-old girl from a wealthy English family, the youngest of three, and an aspiring writer. Her older sister Cecilia (Keira Knightley) is educated at Cambridge University alongside Robbie Turner (James McAvoy), the son of their housekeeper (Brenda Blethyn), whose school fees are paid by Cecilia’s father. Though Robbie is headed for medical school soon, he is spending the summer gardening on the Tallis estate. The ginger-haired Lola Quincey (Juno Temple), age fifteen, and her younger twin brothers, Jackson and Pierrot (Felix and Charlie von Simson), are cousins of Briony and Cecilia who are visiting the family amidst their parents’ divorce. Lastly, Leon (Patrick Kennedy) â€“ Briony and Cecilia’s brother â€“ brings home a friend named Paul Marshall (Benedict Cumberbatch), who owns a chocolate factory that is acquiring a contract to produce army rations. The Tallis family is planning a special dinner, to which Leon happily invites Robbie, who accepts, much to Cecilia’s annoyance.

Briony has just finished writing a play entitled The Trials of Arabella, which she describes being as about “the complications of love”.[4] Her cousins, however, are being unmanageable about staging the play, and she is considerably frustrated. Alone in her bedroom, she witnesses a significant moment of sexual tension between Robbie and her sister by the fountain, when her sister strips down to her underwear and dips into the fountain, to retrieve the lost part of a vase that Robbie has clumsily broken. Because Briony cannot hear what the two are saying, and has witnessed only a fraction of the scene, she misunderstands its dynamics, and the seed of her misplaced distrust in Robbie is sown.

…

The film suddenly shifts forward to 1999, when an elderly Briony (Vanessa Redgrave), interviewed on television (by Anthony Minghella) about her latest novel Atonement, is overcome with emotion and memory. She reveals that she is dying of vascular dementia, and that this novel will be her last, but that it is also her first, as she has been drafting it intermittently since her time at St Thomas’s. Briony admits that the story is autobiographical and expresses great remorse at her actions. She admits that the end of the novel is, in fact, a fiction; in reality, both Robbie and Cecilia died before Briony could make amends, Robbie succumbing to septicemia the day before the evacuation at Dunkirk, and Cecilia perishing in the Ballham Tube Station flooding. Briony explains that she has altered the ending to give her sister and Robbie the chance at the happiness they both deserved, and which she took away from them. The film closes with a scene of a simple, seaside bliss between Cecilia and Robbie, together at long last. The scenery of the English cliff-side beach around them echoes that from a postcard that Cecilia gave Robbie on his departure for duty, as a promise that they would be together someday.